1. A process for preparing photoluminescent samarium-doped titanium dioxide comprising:
(a) precipitating a mixture comprising hydrated titanium oxide, a source of samarium, and a separable filtering agent to form a precipitated mixture comprising precipitated samarium-doped hydrated titanium oxide and the separable filtering agent;
(b) filtering the precipitated mixture to form a filter cake comprising the precipitated samarium-doped hydrated titanium oxide and the separable filtering agent;
(c) calcining the precipitated samarium-doped hydrated titanium oxide and separable filtering agent at a temperature of greater than about 300 C to form a mixture comprising samarium-doped titanium dioxide and the separable filtering agent; and
(d) removing the separable filtering agent to recover samarium-doped titanium dioxide particles.
2. The process of claim 1 wherein the mixture comprising hydrated titanium oxide and the separable filtering agent is prepared by reacting titanium tetrachloride or titanium oxychloride with MOH wherein M is selected from the group consisting of NH4, Group 1 metal, and mixtures thereof, in the presence of a solvent.
3. The process of claim 2 wherein the Group 1 metal is selected from the group consisting of Na, K, Li and Rb.
4. The process of claim 2 wherein the solvent is selected from the group consisting of water, water containing at least one metal halide, water containing at least one ammonium halide, neat alcohol, alcohol containing at least one metal halide and alcohol containing at least one ammonium halide, aldehyde, ketone, nitrile, and ether and mixtures thereof.
5. The process of claim 4 wherein the alcohol is selected from the group of methanol, ethanol, n-propanol, iso-propanol, and butyl alcohol isomer and mixtures thereof.
6. The process of claim 1 wherein the separable filtering agent is MCl wherein M is selected from the group consisting of NH4, Group 1 metal, and mixtures thereof.
7. The process of claim 6 wherein the Group 1 metal is selected from the group consisting of Na, K, Li and Rb.
8. The process of claim 2 wherein the precipitating step is carried out at a pH of about 2 to about 3.
9. The process of claim 8 wherein the samarium-doped titanium dioxide particles are predominantly in the rutile phase.
10. The process of claim 1 wherein the calcining temperature is above about 300\xb0 C.
11. The process of claim 1 wherein the separable filtering agent is NH4Cl.
12. The process of claim 1 wherein the separable filtering agent is removed by washing with water or a solution comprising water.
13. The process of claim 1 wherein the samarium-doped titanium dioxide particles are exposed to heat at a temperature up to and including 800\xb0 C.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A lens apparatus configured to be detachable with respect to a lens-interchangeable image capturing device, and the lens apparatus includes an aperture plate having a plurality of openings, and includes a control mechanism which places the aperture plate at a specified position on an optical path and retracts the aperture plate from the specified position in accordance with external instructions, comprising:
a unit which holds a pattern of openings and non-openings of the aperture plate as a pattern image; and
a transmission unit which transmits the pattern image to the lens-interchangeable image capturing device when the control mechanism places the aperture plate at the specified position on the optical path in accordance with the external instruction.
2. The apparatus according to claim 1, wherein said transmission unit further transmits, to the lens-interchangeable image capturing device, size information indicating a size of an area on the aperture plate, which corresponds to one pixel of the pattern image.
3. The apparatus according to claim 1, wherein said transmission unit further transmits, to the lens-interchangeable image capturing device, a value of an F-number representing an aperture ratio which gives an amount of light transmitted through a lens, which is reduced by the aperture plate.
4. The apparatus according to claim 1, wherein the pattern image is a binary image obtained by assigning different bit values to the respective openings and non-openings.
5. The apparatus according to claim 1, wherein the pattern image is a multilevel image obtained by assigning pixel values corresponding to transmittances of light to the openings.
6. A control method for a lens apparatus configured to be detachable with respect to a lens-interchangeable image capturing device, and the lens apparatus includes an aperture plate having a plurality of openings, and includes a control mechanism which places the aperture plate at a specified position on an optical path and retracts the aperture plate from the specified position in accordance with external instructions, comprising:
transmitting a pattern of openings and non-openings of the aperture plate as a pattern image to the lens-interchangeable image capturing device when the control mechanism places the aperture plate at the specified position on the optical path in accordance with the external instruction.